Insider with Robert Harley -- Coming up in TAS

Jan 3 - One of the great mysteries of digital audio (to me, at least) is how CD transport-mechanism quality affects the sound. I'm not talking about the differences between transports as a whole, but of the mechanism that spins the disc and reads the data. (The sonic differences between transports are the result of jitter, or timing variations, in their digital outputs, which is now a well-documented phenomenon.)

But here's the conundrum: every CD transport mechanism recovers the same ones and zeros from the disc, whether that mechanism is a flimsy plastic job found in a $99 universal-disc player or the massive VRDS mechanism in a $13,000 Esoteric transport. You can prove this by conducting a bit-for-bit comparison between the two datastreams. The data recovered from a CD undergo lots of processing in integrated circuits, which one would think would remove timing variations. In addition, it's possible to clock the data through buffer, which should remove jitter.

Here's one more piece of the mystery. Nakamichi's 1000 CD transport, which has an acoustic seal on the door to the slot-loading mechanism, sounds better with the door closed. In other words, acoustic energy from the loudspeakers impinging on the disc and transport results in audible degradation.

So why do transport mechanisms sound different? And why would isolating the disc and transport mechanism from acoustic energy affect the sound?

I'll tackle these questions in my review of the Esoteric P-03 Universal Transport and D-03 Digital-to-Analog Converter in Issue 171.